Stacked plate heat exchanger

ABSTRACT

A stacked plate heat exchanger having a structure that can be temporarily fixed by a simple structure in brazing, without using additional expensive parts includes a top plate, a bottom plate and a plurality of inner plates, wherein an upwardly bent tab part is formed on at least one of the plates, a cutout part is formed in plates other than the plate on which the tab part is formed, and each plate is stacked and fixed to one another with the tab part and the cutout part in a fitted state.

BACKGROUND OF THE INVENTION

The present invention relates to a stacked plate heat exchangerapplicable for a cooler and the like to cool electronic devices such asan inverter.

Heretofore, as a stacked plate heat exchanger (solid cooler) applicablefor a cooler for electronic devices such as an inverter and the like,there are known a cup plate structure in which inner plates having aflow path are stacked and surrounded with a top plate in a flat plateshape and a bottom plate in a cup shape, as well as a completely stackedstructure in which they are sandwiched with a top plate and a bottomplate both having a flat plate shape.

With respect to these stacked plate heat exchangers, generally the wholeof a heat exchanger is integrally brazed and manufactured, but, inbrazing, inner plates, a cup plate and the like are necessarily stackedand temporarily fixed in a positioned state. As methods of temporaryfixing, a method of welding an outer peripheral part of a stacked body,and a method of using a special fixing jig are known. However, weldingof an outer peripheral part causes such problems that the manufacturingprocess becomes considerably complex and welding marks remain also in afinished product, and in the case of using a special fixing jig, thereis such a problem as increase in cost by that.

In Japanese Patent No. 3026315, a manufacturing method of a stackedplate heat exchanger is disclosed. In the method in Japanese Patent No.3026315, a plurality of plates, in which a hole other than a coolantflow path is separately formed, are stacked and a pipe for temporaryfixing, for example, a pipe such as a grooved spring pin is insertedinto the hole to temporarily fix the respective plates to one another,and brazing or the like is performed in the state.

SUMMARY OF THE INVENTION

In the method in Japanese Patent No. 3026315, an expensive part such asa grooved spring pin is necessary and the number of parts becomes largebecause such a part and the plate are parts of mutually separatedbodies. Accordingly, there are such problems that manufacturing costrises in accordance with those problems and manufacturing operabilityalso deteriorates.

The present invention provides a novel stacked plate heat exchanger thatsolves these problems, configured as follows.

A first invention of the present invention is a stacked plate heatexchanger including a top plate, a bottom plate and a plurality of innerplates, configured such that an upwardly bent tab part is formed on atleast one of the plates, a cutout part is formed in plates other thanthe plate on which the tab part is formed, and each plate is stacked andfixed to one another with the tab part and the cutout part in a fittedstate.

A second invention of the present invention is configured, in the firstinvention, such that the tab part is formed in a rectangular shape witha pair of side surfaces and an end part, the cutout part is formed in arectangular shape with a pair of side surfaces and a bottom surface,both side surfaces of the tab part abut on both side surfaces of thecutout part, respectively, and a surface of the tab part in the bentdirection is separated from the bottom surface of the cutout part.

A third invention of the present invention is configured, in the secondinvention, such that the cutout part is formed in a periphery edge partof the plate.

A fourth invention of the present invention is configured, in the thirdinvention, such that the plate on which the tab part is formed isarranged at an intermediate layer excluding the uppermost layer and thelowermost layer in a plurality of the inner plates.

A fifth invention of the present invention is configured, in the thirdinvention, such that the tab part is formed on at least one of the topplate and the bottom plate.

The first invention is configured such that an upwardly bent tab part isformed on at least one of plates, a cutout part is formed in platesother than the plate on which the tab part is formed, and the plates arestacked and fixed to one another with the tab part and the cutout partin a fitted state.

The stacked plate heat exchanger configured as described above has asimple structure that suppresses complexity of structure and increase incost. In the manufacturing process thereof, the use of expensive partsis unnecessary, and it becomes possible to temporarily fix plates simplywith low cost by a method in which the increase in the number of partsis suppressed.

The second invention is configured such that the tab part has arectangular shape with a pair of side surfaces and an end part, thecutout part has a rectangular shape with a pair of side surfaces and abottom surface, both side surfaces of the tab part abut on both sidesurfaces of the cutout part, respectively, and the surface of the tabpart in the bent direction is separated from the bottom surface of thecutout part.

As a result of the configuration, in manufacturing, even in the caseswhere the upwardly bent part of the tab part, that is, a bent edge partof the tab part is slightly curved or a certain variation is generatedin upwardly bent angles due to a manufacturing error or the like, theplate is prevented from running on the edge part portion in the fitting.Then, the tab part does not interfere with the bottom surface of thecutout part and consequently temporary fixing can be performed moresurely and accurately. As a result, a more accurate heat exchanger canbe obtained.

The third invention is configured such that the cutout part is formed ina periphery edge part of the plate. As a result of the configuration, inthe manufacturing process, it becomes possible to upwardly bend the tabpart and then plates are stacked and temporarily fixed, or to stackplates and then the tab part is upwardly bent to thereby performtemporary fixing. As a result, a degree of freedom in temporary fixingwork increases and the optimum temporary fixing work becomes possible inaccordance with a plate configuration and/or manufacturing process.

The fourth invention is configured such that a plate on which the tabpart has been formed is arranged to an intermediate layer excluding theuppermost layer and lowermost layer in a plurality of the inner plates.As a result of the configuration, in manufacturing, plates havingdifferent cutout positions each other may be arranged on an upper andlower side of the intermediate layer. Consequently, two types of innerplates having different flow path specifications may be combined on theupper and lower sides of the intermediate layer, without erroneousarrangement, to be temporarily fixed.

The fifth invention is configured such that the tab part is formed on atleast one of the top plate and bottom plate. As a result of theconfiguration, in manufacturing, the entire core of a heat exchanger,not only the inner plates, may be integrally and temporarily fixed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an exploded perspective view of respective members intemporary fixing of a stacked plate heat exchanger of the presentinvention according to a first embodiment.

FIG. 2 illustrates a perspective view showing a state where the stackedplate heat exchanger of FIG. 1 is temporarily fixed.

FIG. 3 illustrates an exploded perspective view of respective members intemporary fixing of the stacked plate heat exchanger of the presentinvention according to a second embodiment.

FIG. 4 illustrates a perspective view showing a state where the stackedplate heat exchanger of FIG. 3 is temporarily fixed.

FIG. 5 illustrates a perspective view showing a tab part and a cutoutpart formed on/in a periphery edge part of an inner plate in the stackedplate heat exchanger shown in FIG. 3.

FIG. 6 illustrates a perspective view showing a fitting process of thetab part and cutout part shown in a VI part in FIG. 5.

FIG. 7 illustrates (A) an exploded perspective view of respective innerplates in temporary fixing, and (B) a perspective view of inner platesafter the temporary fixing, in a third embodiment of the stacked plateheat exchanger of the present invention.

FIG. 8 illustrates (A) an exploded perspective view of respective innerplates in temporary fixing, and (B) an enlarged perspective view showingthe B part in (A), in a fourth embodiment of the stacked plate heatexchanger of the present invention.

FIG. 9 illustrates (A) an exploded perspective view of respective innerplates, (B) an enlarged perspective view showing the B part in (A), and(C) a partially enlarged cross-sectional view seen along the C-C arrowin (B), in temporary fixing in a fifth embodiment of the stacked plateheat exchanger of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates a first embodiment of a stacked plate heat exchanger,and shows respective members when temporary fixing is performed as anexploded perspective view. A heat exchanger 1 has a completely stackedstructure, and includes a top plate 2, a bottom plate 3 and a pluralityof inner plates 4 to be a heat exchange part.

Material of respective plates is a metal such as aluminum (includingalloys) and stainless steel, which may be a natural material or acladding material in which a surface of mother material is covered witha brazing material. Incidentally, in the case of a natural material, itis used by applying a brazing material to a portion to be joined.

The planar shape of respective plates is formed as a rectangular shape(specifically rectangle). The top plate 2 has a fluid inlet pipe 5 and afluid outlet pipe 6 for cooling water or the like, and is provided witha bolt hole 7 at four corners thereof for fixing the heat exchanger 1,to an object to be fixed, for example. At four corners of respectiveinner plates 4 and the bottom plate 3, too, bolt holes 8 and 9 areprovided so as to coincide with the bolt hole 7.

At the center part of each of four periphery edge parts of the bottomplate 3, a tab part 10 is respectively formed. When the bottom plate 3is molded, the tab parts 10 in a rectangle projecting in the surfacedirection are formed integrally at positions where respective tab parts10 are to be formed. By upwardly bending the projecting part in 90degrees, the tab part 10 having an angle as illustrated in the drawingis formed. The height of the tab part 10 in this embodiment coincideswith the total thickness of the bottom plate 3, a plurality of the innerplates 4 and the top plate 2.

In four periphery edge parts in the top plate 2 and respective innerplates 4, cutout parts 11 having rectangular planar shapes are formed.Positions of the respective cutout parts 11 match positions of therespective tab parts 10 formed on the bottom plate 3 as shown byrespective arrows.

FIG. 2 illustrates a perspective view showing a state where a stackedplate heat exchanger in FIG. 1 is temporarily fixed. The top plate 2,the bottom plate 3 and a plurality of the inner plates 4 are stacked inclose contact with each other, and respective tab parts 10 formed on thebottom plate are fitted to cutout parts 11 formed in the top plate 2 andrespective inner plates 4.

In order to stack and temporarily fix these from a decomposed state inFIG. 1 to a state in FIG. 2, each cutout part 11 of respective innerplates 4 is made to coincide with each tab part 10 of the bottom plate3, and in the state, while each tab part 10 is fitted to each cutoutpart 11 corresponding thereto, these are stacked. Subsequently, onto theupper surface of the stacked inner plates 4, the top plate 2 is stacked.On this occasion, in the same way as the inner plate 4, the stacking isperformed, fitting each of tab parts 10 to each of cutout parts 11 eachother.

As an alternative method, a plurality of inner plates 4 are stacked inadvance, the top plate 2 is arranged to the stacked body and then abottom plate is arranged to the bottom surface of the stacked body, andrespective tab parts 10 are upwardly bent to perform the fitting atonce. Moreover, by increasing the length of the tab part 10 formed onthe bottom plate 3 up to reach the top plate 2, the top plate 2, theinner plate 4 and the bottom plate can also be temporarily fixed alltogether.

Each plate stacked as described above can be stacked with high accuracyand easily on the basis of a positioning effect caused by the fitting ofthe tab part 10 and the cutout part 11. Then, the temporarily fixedstacked body as illustrated in FIG. 2 is mutually fixed by brazing orthe like.

FIG. 3 illustrates a second embodiment of the stacked plate heatexchanger, in which respective members when temporary fixing isperformed are shown as an exploded perspective view. The heat exchanger1 has a cup plate structure. A different point of a heat exchanger 1 ofthis embodiment from the heat exchanger 1 of the completely stacked typein FIG. 1 is a combination form of the top plate and the cup-shapedbottom plate, and the others are configured in the same way.Accordingly, the same sign is given to the same part as that in the heatexchanger 1 in FIG. 1, and overlapping explanation will be omitted.

In FIG. 3, the bottom plate 3 configuring the heat exchanger 1 is formedin a cup type having a short side wall at a periphery edge part insteadof the flat plate shape in FIG. 1. It is configured such that the topplate 2 is formed in a flat plate shape, and that the periphery edgepart thereof can be mounted on a flange formed on the upper part of theshort side wall of the bottom plate 3.

In this embodiment, on the periphery edge part of the inner plate 4 tobe lain at the lowermost tier in stacking, three tab parts 10 areformed. In the inner plate 4, as shown in the drawing, one end part isformed in a trapezoidal shape and the other end part is formed in anapproximately rectangular shape, and the tab parts 10 are formed on twoslopes of the trapezoidal end part and on the center part of therectangular end part.

In the periphery edge part of each of the other inner plates on which notab part 10 is formed, three cutout parts 11 are formed. Positions ofeach cutout part 11 match, as shown according to arrows, the positionsof tab parts 10. Then, by

fitting each of the tab parts 10 on the inner plate 4 at the lowermosttier to each of the cutout parts 11 in the other inner plates 4, aplurality of the inner plates 4 are temporarily fixed one another.

FIG. 4 illustrates a state where the inner plates 4 having beentemporarily fixed one another as described above are fixed to oneanother by brazing or the like, subsequently the bottom plate 3 isarranged on the bottom surface side thereof, and then the periphery edgepart of the top plate 2 arranged on the upper surface side is mounted onthe flange at the upper part of side wall of the bottom plate 3. Afterthe assembling into the state as illustrated in FIG. 4, respectivemembers of the top plate 2, the inner plate 4 and the bottom plate 3 canbe brazed all together and fixed.

FIG. 5 illustrates only a part of inner plates shown in FIG. 3, in whicha range of a sign VI shown with a dashed one-dotted line in the drawingis a part of the tab part 10 and the cutout part 11. Note that, in theexample shown in FIG. 5, there is shown the tab part 10 in a statebefore being upwardly bent, that is, the tab part 10 in a state parallelto the surface of the inner plate. A fitting process of the tab part 10and the cutout part 11 formed as described above is shown in FIG.

6.

FIG. 6(A) shows the same state as FIG. 5 before the fitting, (B) showsthe state after the fitting, and (C) shows a partially enlargedcross-sectional view in (B) seen in a C-C arrow direction.

As shown in FIG. 6(A), the tab part 10 formed on a periphery edge partof the inner plate 4 lying on the lowermost tier in stacking is formedin a long and thin rectangular shape having a pair of side surfaces 12and 13 parallel to each other and an end part 14 forming the tip ofthese, and, on each outside of side surfaces 12 and 13, a gap part 15 ina long and thin rectangular shape is provided.

The length in a longer direction of the tab part 10 is set to a valuematching the total thickness of the other inner plates 4 on which no tabpart 10 is formed. Incidentally, two gap parts 15 are provided in orderto make the upward bending of the tab part 10 easy. Moreover, eachbottom surface position in two gap parts 15 works as a starting pointpart when the tab part 10 is to be upwardly bent.

Each cutout part 11 formed in the other inner plates 4, on which no tabpart 10 is formed, is formed in a rectangular shape having a pair ofside surfaces 16 and 17 parallel to each other and a flat bottom surface18 orthogonal to these side surfaces 16 and 17, as shown in FIG. 6(B),and a space between the pair of side surfaces 16 and 17 is set to avalue matching the space between side surfaces 12 and 13 of the tab part10, that is, a value that can secure and maintain suitable fittingstrength.

When the inner plate 4 on which the tab part 10 is formed and aplurality of the inner plates 4 on which no tab part 10 is formed are tobe stacked following an arrow in FIG. 6(A), each of periphery edge partsof all the inner plates 4 is made to coincide with each other. Byupwardly bending the tab part 10 according to an arrow in FIG. 6(B) inthe coincided state as described above, the tab part 10 and a pluralityof cutout parts 11 are fitted at a time.

As shown in FIG. 6(C), in the state where the tab part 10 has beenupwardly bent and fitted to the cutout part 11, a surface 19 of the tabpart 10 in the bent direction, that is, the surface facing the bottomsurface 18 of the cutout part 11 in the upwardly bent state is separatedwith a predetermined space from the bottom surface 18 of the cutoutpart. The space of the separation can be set as intended by selectingpositions of flat bottom surfaces in two gap parts 15 of the tab part10, in other words, a space between the position to be the start pointpart when the tab part 10 is to be upwardly bent and a position of thethe bottom surface 18 of the cutout part 11.

As a consequence of setting the surface 19 of the tab part 10 in abending direction to be separated from the bottom surface 18 of thecutout part with a predetermined space in this way, as described above,even if the bent edge part of the tab part is slightly curved orslightly varies in angle, the plate is surely prevented from running onthe bent part in the fitting. Moreover, the tab part does not interferewith the bottom surface of the cutout part, the temporary fixing can beperformed more surely with high accuracy.

FIG. 7 illustrates a third embodiment of the stacked plate heatexchanger, in which (A) shows an exploded perspective view regardingrespective inner plates in the temporary fixing, and (B) shows aperspective view of the inner plates after the temporary fixing.Different points of this embodiment from the inner plate 4 shown in FIG.3 are only the shape of the tab part 10 and the shape of the cutout part11 to be fitted thereto, and the others are configured in the same way.

As shown in FIG. 7(A), in the longer direction of the inner plate 4, oneof end parts thereof is formed in a trapezoidal shape and the other endpart is formed in an approximately rectangular shape, and each of thetab parts 10 is formed on two portions in the inside separated from theperiphery edge part of the end part of trapezoidal shape and on oneportion at the periphery edge part of the end part of rectangular shape.The tab parts 10 formed on two portions in the inside separated from theperiphery edge part of the end part of trapezoidal shape are upwardlybent to the outside in width direction of the inner plate 4 formed in along and thin shape.

This tab part 10 is formed in a long and thin rectangular shape having apair of side surfaces parallel to each other and an end part forming thefront edge thereof in the same way as the tab part 10 shown in FIG. 6.Moreover, the length thereof is set, in the same way as the example inFIG. 6, to a value matching with the total thickness of the other innerplates 4 on which no tab part 10 is formed. Incidentally, the tab part10 formed on one portion of the periphery edge part of the end part inrectangular shape has also the same shape.

The cutout parts 11 in the other inner plates 4 on which no tab part 10is formed have different shapes in the trapezoidal end part and in therectangular end part of these inner plates 4. That is, the cutout part11 in the end part of trapezoidal shape is formed of a hole part in along and thin rectangular shape. Length in the longer direction in thehole part of a rectangular shape is a value matching the space of sidesurfaces of the tab part 10 to be fitted thereto, in other words, is setto a value that can secure and keep a suitable fitting strength. On theother hand, the cutout part 11 in the end part of the rectangular shapeis formed in the same shape as the cutout part shown in FIG. 6.

When respective inner plates 4 shown in FIG. 7(A) are stacked and thetab parts 10 and respective cutout parts 11 are mutually fitted andtemporarily fixed, a state in FIG. 7 (B) is given. In FIG. 7(B), at theend part of the trapezoidal shape in the inner plates 4, a pair of thetab parts 10 on the inner plate 4 lying on the lowermost tier arelinearly inserted into the cutout parts 11 in respective inner plates 4lying on the upper side stacked thereon to thereby be fitted to eachother. On the other side, at the end parts of the rectangular shape inthe inner plates 4, a pair of the tab parts 10 on the inner plate 4lying at the lowermost part are upwardly bent and fitted from a lateraldirection to the cutout parts 11 of respective inner plates 4 stacked onthe upper side.

FIG. 8 illustrates a fourth embodiment of the stacked plate heatexchanger, in which FIG. 8(A) is an exploded perspective view ofrespective inner plates when they are temporarily fixed, and FIG. 8(B)is an enlarged perspective view of a B part shown in FIG. 8(A). Eachinner plate of this embodiment has a shape similar to that of the innerplate 4 shown in FIG. 7, and one of end parts in the longer direction isformed in a trapezoidal shape and the other end part is formed in anapproximately rectangular shape. However, in the embodiment, acirculation hole for a fluid to be formed in the inner plate isvertically classified into two types bordering approximately the centerportion of the number of stacking tiers.

That is, circulation holes of inner plates 4 on the upper side in FIG.8(A) are aligned approximately over the entire surface of the plate, butcirculation holes of inner plates 4 on the lower side are aligned with aspace over the plate surface. A heat exchange performance of innerplates 4 stacked in this way is higher on the upper tier side ascompared with the lower tier side. With respect to a heat exchangerbased on the inner plate configuration, for example, electric parts thatrequire a high heat exchange performance can be arranged on the outersurface (top surface) on the upper tier side, and electric parts forwhich a heat exchange performance may be slightly low can be arranged onthe outer surface (bottom surface) on the lower tier side. Consequently,two types of cooling becomes possible with a single heat exchanger, andan overall heat exchange efficiency can also be improved.

In FIG. 8(A), on one inner plate 4 lying at approximately the centralportion of inner plates 4 to be stacked, a plurality of tab parts 10 areformed, and in the other inner plates 4, cutout parts 11 are formed. Onthe inner plate 4 on which tab parts 10 are to be formed, on threepositions of the periphery edge part in the end part of trapezoidalshape thereof, tab parts 10 each having a rectangular shape are formed,in which, as shown in FIG. 8(B) in an enlarged state, the tab part 10 atthe center of the periphery edge part is formed downward and tab parts10 lying on right and left sides of the periphery edge part andsandwiching the downward one are formed upward. Moreover, on threepositions of the periphery edge part of the end part in rectangularshape, too, tab parts 10 each having a rectangular shape are formed, inwhich the tab part 10 at the center of the periphery edge part is formedupward, and tab parts 10 lying on right and left sides of the peripheryedge part and sandwiching the upward one are formed downward.

Each cutout part 11 of respective inner plates 4 lying on the upper tierside, on which no tab part 10 is formed, is formed in a rectangularshape in a position corresponding to the upward tab part 10 in the innerplate 4 on which tab parts 10 have been formed. On the other hand, eachcutout part 11 in the plurality of inner plates 4 lying on the lowertier side, on which no tab part 10 is formed, is formed in a rectangularshape in a position corresponding to the position of the downward tabpart 10 in the inner plate 4 on which the tab parts 10 are formed.

The inner plates 4 in a plurality of tiers configured as described aboveare temporarily fixed by fitting tab parts 10 formed on one inner plate4 lying approximately the central portion to cutout parts 11 formed inthe other inner plates 4 each other. When the fitting is to beperformed, a process similar to the fitting process shown in FIG. 6 maybe used, but, in some cases, the tab parts 10 may also be fitted in astate formed upward or downward to the cutout parts 11, as shown in FIG.8(A).

As described above, in this embodiment, the location of the upward tabpart 10 and the location of the downward tab part 10 are different fromeach other. The reason is that fitting locations of respective innerplates 4 lying on the upper tier side do not mutually overlap thefitting locations of respective inner plates 4 lying on the lower tierside to prevent erroneous assembling.

FIG. 9 relates to a fifth embodiment, in which FIG. 9(A) is an explodedperspective view of respective inner plates when the temporary fixing isperformed, FIG. 9(B) is an enlarged perspective view showing a B part inFIG. 9(A), and FIG. 9(C) is a partially enlarged cross-sectional viewseen from a C-C arrow direction in FIG. 9(B). An inner plateconfiguration of this embodiment is a modified example of the innerplate configuration shown in FIG. 8. Two different points from theembodiment in FIG. 8 are that an inner plate 4 on which the tab part 10is to be formed is an inner plate 4 to be stacked in contact with theupper side of the lower most tier, and that a fitting structure betweena part of the tab parts 10 and the cutout part 11 in the inner platelying at the lowermost tier is different.

In the inner plate 4 on which the tab part 10 is to be formed, at threeportions in a peripheral part thereof, tab parts 10 in an upwardrectangular shape have been formed in the same way as that in theembodiment in FIG. 8. In addition, as shown in FIG. 9(B) in an enlargedstate, a tab part 10 a in a short columnar shape (so-called a halfblanking dowel type) is formed at four positions.

Cutout parts 11 of respective inner plates 4 lying on the upper tierside, on which no tab part 10 is formed, are formed at positionscorresponding to the upward tab parts 10, and have a rectangular shapein the same way as that in the embodiment in FIG. 8. On the other hand,a cutout part 11 a in the inner plate 4 lying at the lowermost tier hasbeen formed in a through hole having a circular cross-section with asize corresponding to the columnar shape of the tab part 10 a.

Fitting between the inner plate 4 on which the tab part 10 is formed andthe inner plate 4 lying on the upper tier side, in which the cutout part11 in a rectangular shape is formed, is the same as that in theembodiment in FIG. 8. On the other hand, fitting between the inner plate4 on which the tab part 10 a in a short columnar shape is formed and theinner plate 4 lying at the lowermost tier, in which the cutout part 11 aconfigured of a circular through hole is formed, is performed as shownin FIG. 9(C) by inserting the tab part 10 a in a columnar shape into thecutout part 11 a configured of a circular through hole.

The stacked plate heat exchanger of the present invention is applicablefor a cooler for cooling electronic devices such as an inverter, and thelike.

1. A stacked plate heat exchanger comprising a top plate, a bottom plateand a plurality of inner plates, wherein an upwardly bent tab part isformed on at least one of the plates, a cutout part is formed in platesother than the plate on which the tab part is formed, and each plate isstacked and fixed to one another with the tab part and the cutout partin a fitted state.
 2. The stacked plate heat exchanger according toclaim 1, wherein the tab part is formed in a rectangular shape with apair of side surfaces and an end part, the cutout part is formed in arectangular shape with a pair of side surfaces and a bottom surface,both side surfaces of the tab part abut on both side surfaces of thecutout part, respectively, and a surface of the tab part in the bentdirection is separated from the bottom surface of the cutout part. 3.The stacked plate heat exchanger according to claim 2, wherein thecutout part is formed in a periphery edge part of the plate.
 4. Thestacked plate heat exchanger according to claim 3, wherein the plate onwhich the tab part is formed is arranged at an intermediate layerexcluding the uppermost layer and the lowermost layer in the pluralityof inner plates.
 5. The stacked plate heat exchanger according to claim3, wherein the tab part is formed on at least one of the top plate andthe bottom plate.